In many cases, it is necessary to test the running condition of the program under the previous operating system.
Sometimes, we also need to test the first run of the program in a pure system.
iVMachine can install multiple earlier versions of macOS operating systems in One device.
On the other hand, iVMachine can select size of display for test app.
One more thing, iVMachine may create a small environment and run the program under Ubuntu Fedora or Debian.

Clone an exist virtual machine:
Copy exist virtual machine folder, paste its to other folder, after that "Mount" the pasted folder, the same virtual machine disappear in list.

There is available OS passed test by myself in MacBook Air M1:
https://djangoserver.hanmingjie.com/article/article_678.html

Please email me [email protected] with any question.